Roofing materials, such as shingles, roll roofing, and commercial roofing, are typically constructed of a glass fiber mat with an asphalt coating on the fibrous mat, and a surface layer of granules embedded in the asphalt coating.
Chopped strand mat, suitable for use in roofing material, generally includes glass fibers because they are of high strength and tend not to shrink during use. The glass fibers are typically formed by attenuating streams of molten glass material from a bushing. The fibers are drawn from the bushing and the fibers are then chopped directly into a container. The chopped fibers are then dispersed in a water slurry which contains surfactants, viscosity modifiers, dispersants and other chemical agents. The fibers and slurry are agitated to disperse the fibers prior to depositing the mixture onto a moving screen where most of the water is removed. Although this generally describes a wet-laid process, a dry-laid process may be used.
A polymeric binder is then applied. A urea-formaldehyde (“UF”) binder is typically utilized for asphalt roofing product applications due to its low cost, compatibility with asphalt and resulting high strength. After application of the polymeric binder, the resulting mat is heated to remove the remaining water and cure the binder. Next, an asphalt coating that typically includes a mixture of oxidized asphalt, mineral stabilizer and possibly polymer additives is applied to the mat, such as by spraying the asphalt onto one or both sides of the mat, or by passing the mat through a bath of molten asphalt in order to place a layer of asphalt on both sides of the mat. A protective coating of granules may be applied to the asphalt-coated mat to provide a roofing material, such as a shingle.
Important properties for a glass mat include dry tensile strength, hot asphalt tensile strength, hot wet tensile strength, and tear strength. These mechanical properties are useful in determining the asphalt roofing product manufacturing and ultimate reinforcing properties in the shingle. Modifications to the glass mats and the binder compositions to improve such properties are desired.
Accordingly, a need continues to exist in the art for binder compositions for glass mats that can meet new and sometimes exceed demanding applications.